Chapter 7: Cardiac Arrest

BACKGROUND

• Cardiac arrest is defined by a triad of derangements:

  • Pulselessness

  • Apnea

  • Unresponsiveness

• This state leads to progressive tissue ischemia and organ dysfunction, which, if not rapidly corrected, can result in irreversible deterioration of cardiac and neurologic function.

• Cardiac arrest occurs in 2% to 6% of pediatric patients who are admitted to the pediatric intensive care unit.

• Cardiac arrest occurs in approximately 16,000 children out of hospital in the United States each year.

• Because of the relative infrequency of out-of-hospital events, pediatric resuscitations are not common for providers outside of the pediatric intensive care unit.

• There continues to be a significant difference in outcomes (e.g., favorable vs. nonfavorable) between patients with in-hospital vs. out-of-hospital events.

ETIOLOGY

• In general, the cause of cardiac arrest falls into one of three categories:

  • Asphyxia

  • Ischemia

  • Arrhythmia

• Adults with cardiac arrest often have sudden, unexpected ventricular fibrillation and often have underlying coronary artery disease, which leads to myocardial ischemia.

• In contrast, pediatric cardiac arrest is rarely caused by a sudden coronary event or arrhythmia.

• Cardiac arrest in children is most often caused by progressive asphyxia from acute hypoxia or hypercarbia, which leads to acidosis and nutrient depletion.

• Ischemic events are the second most common etiology in pediatrics.

• Ischemic events occur secondary to inadequate myocardial oxygen delivery, which in children occurs most commonly in the setting of sepsis, hypovolemia, or myocardial dysfunction.

• Arrhythmias account for the smallest number of cardiac arrest events in pediatric patients, comprising only 10% of events.

PHASES OF CARDIAC ARREST

• Cardiac arrest can be broken down into four phases:

  • Prearrest

  • No flow (untreated cardiac arrest)

  • Low flow (cardiopulmonary resuscitation [CPR])

  • Postresuscitation

PREARREST

• Pediatric patients with in-hospital cardiac arrest may have physiologic changes in the hours leading up to their arrest.

• Because the majority of pediatric cardiac arrests occur secondary to progressive asphyxia or ischemia, recognition and treatment of respiratory failure and shock states may prevent a number of arrest events from occurring.

• The Pediatric Advanced Life Support (PALS) course was designed to reduce the number of cardiac arrests by improving the early recognition of these conditions.

• Care during this phase should focus on:

  • Identifying and treating reversible conditions

  • Optimizing patient monitoring

  • Providing rapid emergency response for patients not already in a health care setting

NO FLOW (UNTREATED CARDIAC ARREST)

• During untreated cardiac arrest, circulation has stopped.

• Responders to cardiac arrest should minimize time in this state in order to optimize patient outcomes.

• Interventions should focus on the initiation of Basic and Advanced Life Support techniques.

LOW FLOW (CPR)

• The low-flow phase begins with the initiation of resuscitation measures (chest compressions).

• Effective CPR improves coronary perfusion pressure and provides cardiac output to support organ viability.

• Even with optimal CPR, cardiac output is only 10% to ...